Monostable Multivibrator Testing Power Transformer Reliability
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Solution Overview
Problem
Existing low-voltage circuit breakers lack continuous monitoring capabilities for power transformers, making it impossible to detect damage or malfunctions, which can lead to failure of the protective function and require immediate transformer replacement.
Innovation Solution
Incorporating a monostable multivibrator connected to the power transformer, which sets a predefined level output based on transformer voltage signals, allowing for continuous testing of power transformer operation by short-circuiting the rectifier circuit when a predefined capacitor voltage is reached, and maintaining this level as long as signals are tapped off within a time determined by the multivibrator's time constant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power transformer is used to supply power to the trip unit, then the protective function is enabled, but continuous monitoring capability is lost
Solution Approach 1:
The patent divides the power supply system into separate channels, with each power transformer (2a, 2b, 2c) independently monitored by its own monostable multivibrator (M1, M2, M3). This segmentation allows individual monitoring of each transformer without affecting the others, resolving the contradiction by enabling continuous monitoring while maintaining the protective function.
Solution Approach 2:
The patent introduces monostable multivibrators as intermediary devices between the power transformers and the monitoring system. These multivibrators convert the transformer operation into testable signals, acting as mediators that enable continuous monitoring capability while preserving the original protective function of the power supply system.
2Power
If a three-phase bridge rectifier is used, then power supply is achieved, but differentiated evaluation of individual transformer currents is prevented
Solution Approach 1:
The patent segments the power supply system by providing separate rectifier circuits (G1, G2, G3) for each power transformer instead of using a single three-phase bridge rectifier. This segmentation allows each transformer's current to be evaluated independently, achieving both adequate power supply and precise differentiated measurement of individual transformer currents.
3Device complexity
If no testing mechanism is implemented, then device complexity is reduced, but damage detection becomes impossible
Solution Approach 1:
The patent implements a self-service monitoring system where the power transformers automatically generate test signals through their normal operation. The monostable multivibrators are triggered by the transformers' own output signals, eliminating the need for external testing equipment or complex additional mechanisms, thus achieving damage detection with minimal added complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables continuous monitoring and testing of power transformers, ensuring the protective function of the switch by indicating correct operation through a digitally processable signal, allowing for timely identification and replacement of faulty transformers.
Implementation Method 1
a power transformer in the form of an iron-cored transformer arranged at the conductor, which power transformer outputs a transformer voltage
Implementation Method 2
a rectifier circuit which charges a capacitor to a predefined capacitor voltage
Implementation Method 3
this capacitor feeding the power supply of the trip unit
Implementation Method 4
the monostable multivibrator remains set, as long as the signals from the power transformer are tapped off within a time determined by the time constant of the monostable multivibrator
Data Source
AI summary
A switch and a method for testing the power transformers of a power supply of the switch are provided, wherein each power transformer generates an analog transformer voltage corresponding to the alternating current, wherein an electronic trip unit, to which each transformer voltage is applied, compares a current derived from each transformer voltage with a current condition, and wherein a rectifier circuit connected to the power transformer charges a capacitor which feeds the power supply of the trip unit. A switching device short-circuits each rectifier circuit when a predefined capacitor voltage is reached. To provide the protective function of the switch, a monostable multivibrator is connected to one pole of each power transformer, wherein each monostable multivibrator is set by the respective transformer voltage and reset after a predefined time, and wherein the level at the output of each monostable multivibrator is used to test the respective power transformer.